Separation of materials of different



T. M. CHANCE SEPARATION OF HATERIAL S OF DIFFERENT SPECIFIC GRAVITIES Nov. 18,, 1930 Original Filed June 28, 1927 Re. 17,873

' Ila/lento! Reissued Nov. 18, 1930" UNITED STATES THOMAS 1m. cnA ca, or

sErAriA'rIo N or mA'rERrALs or MEBIQN, PENNSYLVANIA DIFFERENT srEcn'rc enAvrrms Original 1V0. 1,685,521, dated September 25, 1928,-Seria1 No. 202,030, filed June 28, 1927. Application to reissue filed August 1?,

My invention relates'to the separationof materials of different specific gravities by means of a fluid mass of relatively high specific gravity, as heretofore disclosed by me in U Patents 1,224,138, May 1, 1917, Coal washing and ore concentration, and 1,559,937, November 3, 1925, Separating materials of different v specific gravities, and particularly to that embodiment in which the'materials floating in said fluid mass are carried through and out of the separating receptacle by means of a cur 1 rent of said fluid mass and water, the fluid mass and a portion of the water overflowing with said lighter material beingreturned to 5 the separating receptacle for re-use therein.

This current of fluid mass and wateris thus used as a conveying element for the removal of said lighter materials. 7

My improvement consists in causing said conveying element to transport saidlighter materials throughca plurality of separators located'withireference to each othenin avertically descending series adapted to establish a hydraulic gradient and a resultant velocity of n flow that will convey the desired quantity of materials through the series, the overflow from the last separator being elevated and delivered into the first separator of the series, thus establishing a closed circuit met-hod of operation.

In carrying out my invention the route of the fluid mass overflowing from each separator:

and also of the layer 'or body of water superposed upon said fluid mass, and discharging with the fluid mass, may be Varied'by returning it in whole or in part to any ofthe separators comprising the series.

The drawing "is a vertlcal elevation and partly cross-sectional view illustrating diagrammatically an assemblage of structures in,by or through which my invention may be carried out.-

r In the drawing, 1 is a I cle or receptacles adapted to" contain ;a separating fluid mass of the described type, the floated material and admixed fluid mass *xtogether with water or other liquid flowing separating recepta- '1930. Serial No. 475,609, 1 I

3, through which most of the sand and water passes and is diverted by launder and chute 4 into separating receptacle orreceptacles 1,

the overflow from which passing out through weir or. weirs 2, upon desanding screen or screens 3, similarly passes through 4 into the separator 1", and thence through 2 and 3 into stay-box 5, whence through conduit 6 it passes into the sand sump 7, from which sand and water are continuously removed and elevated by pump 8 through conduit 9 and delivered by inlet chute 10 into separating receptacle 1.

The said sump 7 is provided with water overflow 11, he return through conduit 6 including the sand and water elevated by pump 8 plus the fluid mass agitation water delivered to the various separating receptacles, as by conduits 12, 12 and 12 and the sprayv Water delivered to the various screens by sprays '13, 13, and 13?, and this excess water rises and discharges through 11', either to waste or for re-use, By-passesfor sand and water are indicated by 14 and 14 fitted with regulating I ates 15 and 15, and by-passes for water only,

y 16, 16 and 16", fitted with regulating gates 17, 17, and 17 A The separatin receptacles may be of any desired shape a apted to contain andmain tain the requisite separating fluid mass and may be fitted With any desired means for reing on descending shaker 21, which in turn passes sand recovered therefrom to 22 for return if desired to sump 7 The drawing shows 3 separating receptacles each of which i'sprovided with vits own set of screens for sizing and desanding the coal fed into each unit, so that the product of each separator is a-finished' product requiring only. desanding and sizing for shipment to markegin some cases some p rticusand chute moving the materials heavier than said fluid adapted to either the treatment of anthracite or bituminous coal in that in anthracite the smaller or steam sizes constitute roughly about one-third of the quantity to be treated and in soft coal the slack is frequently of about the same relative quantity, so that this layout may be advantageously utilized by dividing the coarser coal into two parts to be treated by the first two separating cones, the finer coal to be treated in the third separator and the first separator may be used for treating the coarser half of the mine output, the

second separator for treating the half of the output constituting the, smaller size, both the separators being operated to produce a finished product, the refuse from the first separator being crushed or otherwise broken Y down and retreated in the third separator for low ash and high ash bony coaland laminated the production of clean refuse and a finished product, or a product of intermediate, grade for retreatment in the second separator. In many cases one of the sep-arating units can be eliminated, efiicient separation being secured with two such units. While my invention primarily is designed for such or similar uses, it may also be used for other purposes and other methods of operation by changes or removal of some of the screens, thus,

l he screen sets 3, 3 and 3 illu'strate-several variations in the mode of operating the three separators 1, 1 and 1 as for example,

1. Screen sets 3 may be-removed and all floated material passed directly from 1 into 40 1, the specific gravity of the fluid mass in 1 bemg adapted to float all high grade coal,

coal and slate, while the fluid mass in 1 is sufficient to float coal of the desired quality, low ash bony coal etc. while pennit'tingafl heavier material to sink, to be removed through the discharge valves, for subsequent cruslung and return to separator 1, 1 or 1 or for retreat-merit by any other process, while the floated coal is screened by screen 3 into large, intermediate and smaller sizes, the two former 'for shipment, to market while the finer sizes are passed-into 1 for treatment at a specific gravity that will give a high grade product and this is then sized into market sizes by screens 3" and is dewatered and desanded, the water, and sand going directly into 5 and 6 for elevation through 8, 9 and 10 to separator 1, or v 2. Separators 1, 1 and l may each be fed with large, medium and small sizes of coal, the floated product of each being screened by 3, 3 and 3 intornarket sizes, the reject from each separator being crushed to smaller-size and returned to the separators for retreatment, or

3. The screen sets 3 and 3 can both be re I rator 1 discharging bony and laminated coal through its refuse discharge for treatment by crushing the coarse material to smaller size and return to separator 1, separator 1 discharging the coal for shipment in mixed sizes or screened into market sizes. By this method desanding screens 3, 3 and 3 are eliminated and the height through which the water and sand must be elevated is materially reduced.

Sand and water not, removed by screens 3, 3 or 3 may be separated by additional screens or other means and returned to the circuit by discharge into sand sump'7. Sand and'water recovered from the heavier material trapped out of the base of the separators may be returned to the circuit in the same manner.

The launders and chutes 4,, 4 and 4* may be provided with means for feeding all or such portion of the sand and/or Water as may be desired into the next succeeding separating receptacle or receptacles, all of which will be readily understood by those skilled in the art, the chutes 14 and 14 fitted with gates 15 and 15 providing such by-passes for the sand and water, and the chutes 16, 16 and 16 fitted withgates 17, 17 and 17', providing similar by-passes for the water only. It will be understood that, Whereas the screens 3 'receive only the intake of chute 10 plus the agitation water used in separator 1 and the spray water from sprays 13, the last screen in'the series receives the summation of all the spray and agitation Water used in the preceding series, unless some of this egccess water'is bypassed from the circuit. This excess water, if by-passed, may be sent directly to stay box 5 or, it free from sand, to the Water overflow. 11. i It will be understood that where a plural ityof separating receptacles is used in series to retreat the products produced in the initial unit, the intervening desanding screen may be eliminated and the material floated. in the one receptacle discharged directly, with its conveying volume of sand and water,

into the next receptacle, the separating sur faces of the various fluid masses lying within the requisite hydraulic gradient to give thedesired velocity of flow. c 'In operating the method of flotational separation by a fluid mass as described in the above mentioned patents, for separating coal from its intermixed impurities, the overflowj of the layer of coal floating at the top of the separating fluid mass usually effects the dis charge of the coal with minimum breakage.

If the coal so cleaned requires retreatment at a difierent specific-gravity to separate it a conveying element. ThlS single unit need into grades of dii i'erent qualities, or requires separate treatment of different sizes, the use of a plurality of separators becomes. necessary.v Also, it is often necessary to use a plurality of separators treating material of like natureto accommodate the, quantity of material to be separated. By my present'invention, such plural separators are served by a single unit, such as a pump or other device,

for reelevating the sand and water used as have no greater volumetric capacity than that of each of the unitsthat would be re= quired for each of a plurality of separators individually operated. Hence if four such separators'are installed, only one-fourth of the volumetric reelevating capacity necessary for individual operation would be required by my present method, and the power absorbed would likewise be greatly reduced, although the elevating head is slightly increased due to the necessary elevation to secure gravitational flow between the separatorsi I have used this method commercially in preparing coal and its intermixed impurities formarket by flotation of the coal in a fluid mass composed of an agitated mixture of sand and water and by the sinking of the intermixed impurities therethrough, reusing sand and water overflowing from one separating receptacle, in a separating receptacle located at a lower e evation.

If desired, the materials to be separated,

may be graded into a plurality of sizes before separation thereof, each size being fed to a separator in which the fluid massis maintained at the specific gravity best adapted to separate the materials composing the size fed thereto, such variation in specific gravity producing cleaned .coal adapted to meet the purposes for which each size is to be used, and this method of use of my present method has likewise been commercially applied by The quantity of floating material which can be made to overflow the discharge weir depends largely upon the quantity of fluid mass and overlying water which is supplied to the separator and overflows the weir. The principles involved can be illustrated by describing the method as used in separating coalfrom its intermixed impurities. If a mixture of sand and water is fed. through chute 10 ing agitation water issuing upwardly from the fluid mass, and thus form an addition to the fluid mass. 'Coal floating in the fluid l mass rises through this addition and floats at the top thereof, each piece projecting upwardly into the'overlying water. To permit the slate to fall ,asuificierrt distance below the discharge weir, a more or less definite time interval must elapse between the time the coal is fed into the apparatus and the time it is dischar ed over the weir, and the surface velocity of ow through the separators must be at such rate as to permit the coal to remain in the separating receptacle for such time interval. If, for example, the period necessary for separation is 5 seconds, and the distancethe coal must travel from the point of feed to the point of discharge is 15 feet the velocity of flow withinthe body of the separator should not be greater than 3 feet per second, but if separation be efl'ected in 3 seconds a velocity of 5 feet per second is permissible. The capacity to take and discharge feed will of course depend upon this velocity and upon the average cross-sectional area of the moving mass of coal within the separator.

In the operation of-a series of separators in which the water and fluid mass overflowing from the first separator are used for the'operation of one or moreseparator's, it is important that all of the separators in the series receive a suflicient volume of water and flu d mass to successfully separate the coal fed into each of the said separators, and that the time interval in each during which separation is effected be sufiicient for proper separation of the material fed into it, which in turn requires of fixed design, may be efl'ected by the regulation of weirs 2, 2 and 2", the adjustment of the various by-passes previously described and the regulation of the quantity of sand and water re-elevated.

The conveying element of my present invention performs the functions of a me-. chanical conveyor such as a chain scraper line, but differs radically from all forms of mechanical conyeyors. veyors the velocity of movement is equal along the entire line whereas in my conveying element the velocity of movement can be varied at will, some por ions thereof movigg athigh velocity while other portions "move. at relatively slow speed. My conveying element can neither push nor pull the materials to be moved, the operative portion being actuated solely by energy supplied by gravity,

, In mechanical conbut its velocity may beincreased or decreased at will by varying the hydraulic gradient in different portions thereof. Energ from an extraneous source-of power is app led solely in elevating the materials ofthe conveying Water to be used as a conveying element is separated from the added agitation and spray water before return to separating receptacle by pump 8, sump 7, serving to perform this separating function. It will be understood that sump 7 may be located above the first separating receptacle 1, and discharge the conveying element constituents directly into chute 10 through a controlled spigot, pump 8 in this event pumping the underflow from screen 3 1 and the various by-passes, and discharging into stay-box 5, said pump being made of suflicient capacity to re-elevate the conveying element, plus the agitation and spray water discharged through the various desanding screens, such as 3, 3 and 3*. If this construction be adopted, overflow 11 of sump 7 may be located'at sufficient elevation above separating receptacle 1 to pass the agitation, water directly into the various separating receptacles Without re-pumping. Under these conditions, pump 8 serves as a re-elevating device for both the conveying element, the agitation and the spray water.

While the chutes 10, 4 and 4 are shown discharging the conveying element into the upper portion of the fluid mass, this is not a condition essential to the operation of my invention. In the separation of very light materials, where low specific gravities of the separating fluid mass are required, it may be desirableto use all or a portion of the conveying element to assist in the agitation of the fluid mass.

' conveying element is introduced at sufficient depth below the upper surface of the separating fluid mass, and under the requisite pressure, to impart the desired agitational work to said fluid mass. If this procedure be adopted, a reduction in the agitation water that would be otherwise required may be made equal to the amount of energy secured from the use of said conveying element as an agitational agent.

In operating my invention the overflow 11 or other outlet from sandsump 7 may be utilized to remove silt and fine light solids as described by me in the reissue of Patent No. 1,559,938, November'3, 1925, Apparatus for separating materials of different specific gravities. i

The sand sump 7 must be large enough to hold a supply of sandto replace that lost from the system by failure to thoroughly desand 4 the separated materials discharged from the plant or lost through overflow 11 from thesand sump andalso to accommodate sand of the'pluralfluid masses which may .be displaced therefrom by failure to remove separated materials through over-feeding or other cause. 7

Under these conditions said The sand thus held in storage may be maintained as a fluid mass having a specific gravity suflicient to float lighter material accumulating therein, the water rising through said fluid mass having suflicient velocity to expel therefrom those lighter particles which are.

slightly larger and those that are smaller than the particles of sand. Such expelled particles then form a secondary fluid mass superposed above the sand and can be removed from the sand sump by the overflow or by tapping off below the level thereof. This also assists 'in maintaining maximum capacity to accommodate sand and hold it as a storage reservoir common to all of the plural fluid masses.

The area of--the upper portion of the sand sump 7 must be so proportioned to the total volume of water that passes upwardly to overflow 11 that the velocity of said water will not carry undesirable volumes of sand out of said sump. To assist in maintaining this condition, the upwardly rising water may be limited in quantity by employing the water by-passes 16, 16 and 16", under which method of operation, the area of the sand sump need be no greater for a plurality of separating units than if but one such unit were used.

One important embodiment of my inven tion therefore is this combination of structures and means whereby a plurality of separating fluid masses may be served by moderate sand sump volumetric capacity which maybe utilized, 1, as a sand storage reservoir common to all of said plural fluid masses, 2, as afclari-fler to prepare water for reuse in agitating said fluid masses and in washing the separated materials, 3, for reconditioning and cleaning the sand for reuse by the removal of small particles of lighter materials,

4, as a storage reservoir to insure uniformity and certainty of supply of water and sand for continuous functioning of the conveying element as already described, '5, for the recovery-as a separate product ofsmall particles of the lighter mateFials, 6, to insure automatic functioning of the absorption of sand by, and of its discharge from, the sand sump as sand is displaced from, and is reabsorbed by, said plural fluid masses, this being attained by proper proportioning of the sand sump structure and,of the volume pumped from the lower part thereof, and/or proper adjustment of the by-passes to limit the quantity of upwardly risingwater in the sand sump to that required for maintaining proper fluidity therein without causing undesirable losses of sand through overflow 11.

It will of course be understood that sand sump 7, pump 8 and conduit 9 may be replaced by such plurality of said devices as it may be desired to use, in which event'the combined capacity .of the plural members need be-no' greater than that required fora ins-rs single unit. In the same way, the separating receptacles 1, 1 and 1 and screens 3, 3 and 3? may be constructed as plural units,*each operating in parallel, and discharging either to a single sand sump 7 or to a plurality of said sumps, the drawing, being a purely diagrammatic arrangement of one form of the general association of elements necessary to my invention. a

In the specification and claims hereof the term sand is intended to mean appreciably coarse granular insoluble material heavier than the liquid used and suitable for mak-' ing a fluid mass of the described type, and the terms water and liquid are intended to mean any liquid suitable for making a fluid mass of the described type.

Having described my invention, claim! 1. A method of separating materials o'r'v difierent specific gravities which consists in immersing said materials in a fluid mass consisting of an a itated mixture of liquid and comminuted so ids heavier than said liquid and substantially'insoluble therein and having a specific gravityintermediate that of the lighter and heavier of said materials, in'

providing a plurality of individual fluid masses of the described type, in locating the top of said fluid masses at vertically diflering elevations, said differences inelevation' depending upon the horizontal distances separating, said bodies, in proportioning the gradients between said fluid masses to per-,

' mit the free flow of liquids by gravity irom the top of the fluid massat a higher eleva-' tion to that of one at a lower elevation, in separately feeding into each of said fluid masses materials to be separated thereby, in causing a mixture of comminuted solids and liquid to be circulated irom a body of such mixture located at an elevation below said fluid masses into and across the higher of said fluid masses, in separatin lighter materials transported by said uid mixture away from said fluid mass from the constitu-. cuts of said mixture and of said fluid mass intermixed therewith, in then passing said circulatingmixture into and across the top of another of said plural se arating fluid -masses, in separating the lig ter materials carried away from said second fluid mass by said circulating mixture, and in returning said circulating mixture, vafter the removal of said -li hter materials into the said body of. said mixture located at said lower level.

. 2. Apparatus for separating materials of difl'erent specific gravities comprising in combination a plurality of receptacles adapted to contain fluid masses consisting of an agitated mixture of liquid andcomminuted solids heavier than said liquid and substantially insoluble therein and having specific .g-ravitiesintermediate that ofthe lighter and heavier of saidmaterals, fluid masses of the 'the application of power extraneously apagitated mixture of'liquid and comminuted tainer adapte means for passingthe mixture after'the redescribed ty e in said plural receptacles, said I receptacles eing located in a' descending series of steps, the vertical height of said 'stepsibeing proportioned to the horizontal masses, a container adapted-to contain said body, means for separating lighter materials transported away from said first fluid mass by said circulating mixture, from the con- J stituents of said mixture and of said fluid mass intermixed therewith, means for passing the mixture after the removal therefrom of thelightermaterials into and across the top of another of said plural separating fluid masses, means for separating the lighter materials carried by said circulating mixture throu h the outlet from said second receptacle irom the, comminuted solids and liquid intermixed therewith, and means for return-' v in said circulating mixture after removal of said light'erimaterials into the body of said mixturein said,container, and means for efi'ecting the circulation of said. mixture by plied to said mixture.

3. Apparatus for separating coalfrom impurities intermixed therewith comprising in .v V combination a plurality of receptacles adapted to contain fluid masses con'sistingiof an solids heavier than said liquid and substantially insoluble therein and having specific gravities intermediate that of said coal and intermixed impurities, fluid masses of the described type in said plural receptacles, said receptacles being located ina'descending series of steps, the vertical height of said steps vbeing proportioned to the horizontal distance separating said receptacles, means for accommodating the free flow of liquids by gravity from the discharge of each receptacle to a receptacle'at a lower elevation than said first receptacle, means for feeding into each of said fluid masses coal and intermixed impurities, means for circulating a mixture of comminuted solids and liquid from a container holding a bod ofsuch mixture and located below said uid masses, into and across the higher of said fluid masses, a conto contain said body, means for separating coal transported away from said first fluid mass by said circulating mixtnre, from the" constituents of said mixture and'of said fluid mass intermixed therewith,

/ plied to said mixture, and means for removto impart additional agitational work the ing said impurities from the lower part of saidsepa-rating receptacles.

4. In a method for separating materials of difl'erent specific gravities by the flotation of the lighter and the sinking of the heavier of said materials in a separating fluid mass consist ng of an agitated mixture of liquid and comminuted solids heavier than said liquid and substantially insoluble therein and hav ing a specific gravity greater than the lighter and less than the heavier of said materials which consists in providing a plurality of separating fluid masses spaced apart laterally and with their surfaces at different elevations proportioned relative to said spacing to provide a determined hydraulic gradient to effect flow of liquids by gravity from the top'of one fluid mass to the next lower; maintaining upon each of said fluid masses a superposed body of said liquid; restraining the overflow of said bodies of liquid-to maintain predetermined depths thereto; feeding materials to be separated into the first of said fluid masses; causing an upper layer of said first named fluid mass in which the lighter of said materials are floatingtogether with liquid of said superposed body to flow away from said first fluid mass whereby said flowing liquid and said flowing layer serve to transport said floating materials therefrom; causing liquid to be introduced into and rise through each of said fluid masses to serveas an agitating agent and to accumulate upon the surface thereof to assist in maintaining said super-. posed bodies of liquid ;'separating from said conveying element lighter materials transported thereby; and returning to said first fluid mass constituents of said conveying element, to replenish-said first fluid mass'and to maintain said superposed' body of liquid thereon.

5. A method according to claim 4 in which constituents of theconveying element are in-. troduced into the separating fluid mass below the surface thereof'under pressure suflicient fluid mass.

6. Apparatus for separating materials of different specific gravities comprising in combination a plurality of receptacles adapted to accommodate separating fluid masses consisting of agitated mixtures of llquld and therein; said receptacles being placed a definite distance apart, and each of said receptacles being placed a definite distance below the next above it, said distances and said eleva-ti-ons being so proportioned as to provide predetermined hydraulic gradients from each ofsaid receptacles to that next below it; means forrestraining the outflowing of said separating fluid masses and of liquid superposed thereon to maintain predetermined depth of overflow to said bodies and to said superposed liquid; means for feeding materials to be separated into the first of said fluid masses; means for-conveying materials outfiowingfrom said receptacles and for transporting said materials therein; means for conveying the'constituents ,of outflowing fluid masses and superposed liquid into ariother of said receptacles located below said first receptacle; means for introducing liquid under pressure into said receptacles below said fluid masses; means for separating from said fluid mass and superposed liquid the lighter materials transported thereby; means for returning to said first fluid mass those constituents of said fluid mass utilized as a con- .veying element; and means for superposing upon said fluid mass liquid required for said conve ing element.

7. n a method for separating materials of "different specific gravities by the flotation of 1 and substantially insoluble therein, said fluid mass being agitated by liquid introduced under pressure below it and rising therethrough, whereby its specific gravity is maintained and controlled at a density greater than the lighter and less than the heavier of said materials, and in which lighter,materials floating in-the upper part of said fluid mass together with that portion of the fluid mass in which they are floating, flow by gravity out of and away from said fluid mass, assisted by the outflowing of liquid superposgl upon said fluid mass, said outflowing fluid') mass and said outflowing liquid acting as a conveying element to convey said floating lighter materials out of and away from said fluid mass, and in which said lighter mate-- rials are separatedfrom the constituents of said conveying element and a portion of the constituents of said conve in element substantially equal to those isco arged are returned to said fluid mass and liquid superposed thereon, the improvement which consists in introducing portions of the constituents of said conveying element below the upper surface of the separating fluid mass under a pressure that will impart additional Work to said fluid mass, whereby the liquid introduced below under pressure to effect agitation may be reduced by a quantity proportional to the energy imparted by causing 10 said conveying element to function as an agitational agent; in feeding materials to be separated into said fluid mass; in causing said fluid mass 50 agitated to float the lighter of said materials and, assisted by said outflowing superposed liquid, to discharge said materials therefrom.

THOMAS M. CHANCE. 

